In recent years, power liberalization has been promoted overseas, and there are countries in which about 30% of power consumption is traded in a power wholesale market. While the structure of a power wholesale market is different from country to country, for example, there is a market called as a day ahead market (DAM) in which bidding is performed for each unit time before one day. A power-selling price in a power wholesale market is determined based on a balance between the demand and supply of power and greatly changes in time.
For this reason, in order for a power generation company to obtain a profit by participating in bidding, it is important to perform an optimal operation in accordance with a power-selling price and variations in the demand of power.
In Patent Literature 1, a technology has been disclosed which includes a step of setting a power-selling price of each period, a step of detecting each operation state that can be taken by a power plant for each period and registering a profit for each transition path reaching the operation state, and a step of finally planning an operation plan of the power plant based on a transition path through which the profit can be maximized. According to this technology, a profit of each period is acquired by decreasing a profit caused in selling power by a loss caused due to power generation variations (an event in which a contracted power generation amount and an actual power generation amount are different from each other).
In Patent Literature 2, a power generation plan/power selling plan generating method including a process of acquiring a probability distribution according to uncertainty factors (variations in the demand for power, variations in the unit price of fuel for power generation, and the like) for a balance generated according to power generation and power selling and a process of displaying the probability distribution in a time series has been disclosed. According to this method, it is disclosed that a correlation between a profit of an operation plan of the current state and a risk can be acquired, and a search for a plan for resolving the risk of the operation plan of the current state can be performed.
In Patent Literature 3, a power plant operation supporting system has been disclosed which includes an operation condition optimization calculating unit calculating an optimal operation condition at which the power generation performance value of a power plant is the maximum based on a probability distribution of power demand predicted values and power trading market price predicted values, a risk evaluating unit calculating and evaluating a risk value for damaging the optimization of the optimal operation condition, and a reserved power optimizing unit.
The reserved power optimizing unit calculates optimal reserved power of a power generation amount capable of responding to a load increase request from customers in a short time and calculates load conditions that are optimal for maintaining the reserved power in terms of cost. One of these optimal load conditions is a rated overload, and, in Patent Literature 3, it is described that, in an operation under a rated overload, an operation cost such as a decrease in the device life due to an unnecessary stress or an increase in the maintenance cost due to the application of stress that is not needed for a plant increases.
In Patent Literature 3, a management system for a power plant planning an operation plan such that a power generation profit is optimal with a life consumption cost and the risk of unplanned plant stop (stop due to a trouble) considered has been disclosed.
Here, a life consumption cost is determined based on the amount of a remaining life consumed for a life cost (a cost taken until replacement after a certain component is consumed from the time of a new product) and is calculated as a product of a remaining life consumption ratio (a ratio at which the remaining life is consumed) and a life cost (life consumption cost=remaining life consumption ratio×life cost).